1. Field of the Invention
The present invention relates generally to an engine mounting arrangement and more specifically to an engine mounting arrangement which includes an elastomeric insulator having a variable volume chamber device associated therewith which chamber may be hydraulically pressurized/depressurized in a timed relationship with the most significant vibration of the engine and in response to changes in vibration amplitude and/or intensity thereof, which occur with change in engine operation.
2. Description of the Prior Art
In a previously proposed dynamic spring constant reducing arrangement shown in FIG. 1 of the drawings, an elastomeric mounting insulator 1 having a hydraulic chamber 2 defined therein, is operatively interposed between an automotive engine 3 and the chassis 4. The hydraulic chamber 2 is fluidly communicated with an actuator arrangement 5 having a variable volume chamber 6 which is contracted and expanded in response to the rotation of a cam 7. The cam 7 in this instance is operatively connected to the crankshaft of the engine (not shown) so as to rotate in synchronism therewith.
The operation of this arrangement is such that, as the engine 3 vibrates in a manner to compress the insulator 1 and thus reduce the volume of the chamber 2 defined therein, the cam 7 is adapted to induce an expansion of the chamber 6 so as to relieve the pressure tending to develop in the chamber 2, and subsequently, as the engine moves away from the chassis 4 and the chamber 2 tends to expand, the cam 7 rotates to a position wherein the chamber 6 is contracted to prevent maintain the pressure in the chamber 2 and prevent same from falling due to the expansion thereof.
However, with this type of arrangement provision must be made within the engine per se, for a suitable shaft which is relatively close to the outer surface thereof and for a mounting site for the actuator device driven by the just mentioned shaft. Hence, the complexity of the engine construction has been unduly increased and further design limitations in that the number of suitable sites at which the actuator may be readily mounted is limited due to the need for the actuator to be relatively close to the shaft via which it is driven and by the limited amount of space available within the engine compartment about the engine, encountered.
Furthermore, this arrangement has been unable to allow for the various changes in vibration which occur with change in engine operation and vehicle running conditions.
A full and detailed disclosure of the above disclosed arrangement may be found in U.S. Pat. No. 4,154,206 issued on May 15, 1979 in the name of LeSalver et al.